1. Field of the Invention
The invention relates to a viscous coupling having a housing which consists of a tubular housing casing and to whose ends there are attached end walls so as to extend radially relative to the longitudinal axis; having a hollow hub which is arranged coaxially thereto in the housing and which, at its two ends, is received in bores in the end walls by means of cylindrical bearing faces so as to be rotatable relative to the housing around the longitudinal axis; having annular outer plates and inner plates partially radially overlapping and arranged alternately in a certain sequence in the inner chamber formed between the housing and the hub; and having a highly viscous fluid, especially silicone oil which at least partially fills the part of the inner chamber not occupied by the outer plates and inner plates, with the outer plates, by means of teeth provided at their outer circumference, being non-rotatably received in inner toothing of the housing extending parallel to the longitudinal axis and with the inner plates, by means of teeth provided in their central bore, being non-rotatably received in outer toothing of the hub extending parallel to the longitudinal axis and with the hub, in its cavity, being provided with further inner toothing for being connected to a shaft.
2. Description of the Related Art
Such a viscous coupling is described in GB-PS 1367 106 for example.
Such viscous couplings are used in the driveline of motor vehicles for example in order to lock, at least to a limited extent, the effect of the differential between the wheels of an axle or between the two axles of a vehicle, or to pass on torque as a result of the speed differentials occurring.
When using such viscous couplings in the axle (e.g. the front axle of a front wheel drive vehicle or in the rear axle of a rear wheel drive vehicle), space is limited. In particular, this applies to fitting such couplings in the front axle differential of a front wheel drive vehicle. Apart from the restricted space conditions, the weight of the vehicle is also significant. The dimensions of the viscous coupling are determined by the free space remaining in the differential drive. As far as the torque transmitting capacity of a viscous coupling is concerned, the mount of overlap of the plates arranged in the inner chamber between the housing and hub of the viscous coupling is also important. The greater the amount of overlap, the greater the torque transmitting capacity.